Picture-projection lamp



W. G. PREDDEY.

PICTURE PBQJECTION LAMP. APPLICATION HLED FEB. 11, 1919.

1,340,499. Patented May 18, 1920.

I lfll/LU' IN VEN TOR.

A TTORNE Y San Francisco, in the county of San F ran- 7 UNITED STATES PATENT oerron WALTER e. PREDDEY, or sAiv FRANCISCO, CALIFORNIA PICTURE-PROJECTION LAMP.

Application filed February 1 1, 1919. Serial No. 276,306.

To all whom if may concern: 7

Be it known that I, WALTER G. Pnnnnnr, a ClillZBIlOf the United States, residing at cisco and State of California, have invented certain new and useful Improvements in 'Picture Projection Lamps; and I do hereby declare the following to be a full, clear, and exact description of the preferred embodiment of this invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, which form a part of this specification.

This invention has for its object to eliminate the numerous undesirable features which are prevalent in the present type of combination picture-projection lamps now commonly in use for projecting both stereopticon and motion pictures. Heretofore it hasbeen necessary to shift the lamp-housing, lamp or lenses in changing over from stereopticon to motion pictures which results in an abrupt pause between the two pictures during the time of change. In apparatus of this type as hitherto constructed the dissolving effect is usually produced by manipulation of the lights in two adjacent lanterns or the manipulationof the shutters of same. Thus while a picture in one of the lanterns is thrown on the screenwith full brilliancy the slide bearing the next picture to be exhibited is inserted in the other lantern, the

, light of which is of course extinguished or so dim as to be practically extinguished; the light in the second lantern is gradually in creased, with the result that the first picture appears to dissolve into the second. ,The successful operation of such an apparatus demands great skill on the part of the operator in manipulating the lights, as both sources must be controlled simultaneously. I have therefore been led to devise my present invention to produce a projecting apparatus which will give perfect dissolvingview effects automatically without the manipulation of any of the several elements of the device by the operator when same is in operation. Thus the principal undesirable features which are prevalent in the present type of combination pictureprojection lamps now commonly in use for projecting both stereopticon and motion pictures, to wit, the manipulation of two sources of light simultaneously or the shifting of any of Specification of Letters Patent.

Patented May 18, 1920.

- the several elements such as lamp-housings,

ing, the same having no moving parts. A

further object is to provide a device of the above description that will produce a perfect transition or dissolving-view effect without the manipulation of any of the several ele ments of same. 9 I j j A still further object is to provide a de-- vice of the above description that will be positive in operation, simple in construction and not liable to get out of order.

With these ends in view my invention consists inthe details of construction and combination of elements hereinafter set forth, and then'specifically describedby the claim. Its construction and operation will be described in detail, referring by numerals and letters to the accompanying drawings forming a part of this specification, and in which similar numerals and letters designate cor- I ing a different means of connecting lamps l;

Referring to the drawings, 1 shows the side walls of lamp-housing, the same con taining lenses 2 and 3 of different focal.

lengths. Incadescent electric lamps 4 are positively mounted in lamp housing 1 the proper focal distance from lenses 2 and 3 by means of lamp sockets 5 which are rigidly attached to the bottom of lamp housing 1. Line wires (1 and a connect the lamps lto a source of E. M. F. by means of a switch 6 and contacts 7 throughan inductive reactance comprising parts 8 and 9.

In carrying out my invention I preferably use a single lamp-housing conta ning both lenses and a lamp for each lens;

1 taken on the although two separate lamp-housings each containing a lamp and lens can be used. The lamps used are a low voltage high amperage type, such as those now commonly used in series lighting the amperage of same being 20 or 30 amperes on verylow voltage. In series with said lamps I preferably employ an inductive reactance for cutting down the voltage of the line to suit the voltage of the lamps, although a capacity reactance will answer the same purpose. switch of any type can be used for the opening and closure of the lines (a and a through the lamps a and reactance' comprising parts 8 and 9.

The operation of this device will then be as follows: The lamps l being positively set the proper focal distance from the lenses, and the lamps connected to a source of E. M. F. through line wires a and (t the switch 6 as shown in Fig. 3 is placed in position to close the circuit for one of the lamps, the core 8 of the reactance is then pushed in the coil 9 of same as per dotted lines and the main switch connecting line wires a and a to service is then closed, the core 8 of the reactance is then pulled out until the desired voltage for the lamps is attained, the core 8 is then permanently locked and does not need-to be moved again unless the voltage of the line should vary. The pictures to be shown are then placed in their proper position in front of the lenses, thus, in front of lens 2 the stereopticon slides are placed and in front of lens 3 the motion picture films are placed. The device is then ready for operation. hen one picture has been shown the switch blade 6 is shifted to the opposite contact lighting the other lamp. The filaments of these lamps are preferably of large volume and require some time to extinguish from incandescence; the larger the filament the longer the time required. It is obvious then that it requires a number of seconds to bring the lamp to its full brilliancy, also to extinguish same from full brillancy, and that by simultaneously turning off one lamp and turning on the other that the picture on the screen will be made to fade away concurrently with the gradual appearance of the succeeding picture, thus automatically producing a perfect transition of the pictures without the manipulation of any of the elements of the device. It is a recognized fact that with a reactance in series an incandescent lamp consuming current will take a great deal longer time to come to full brilliancy than without a reactance in series with same. Thus I employ the reactance to lengthen the time of transition of the pictures, and particularly when small amperage lamps are used, the same coming up to full lorilliancy and extinguishing from full brilliancy too fast. t is obvious that inductive or capacity reactance may be used, also, the lamp circuits or the lamp filaments may be so arranged as to produce the necessary inductance.

lVhile I have illustrated. and described the preferred construction and arrangements of the various parts, it will be obvious from the foregoing description that the device is susceptible of considerable modification', without departing from the essential features or sacrificing any of the advantages thereof come within the scope of the claim appended thereto.

Having explained the nature of this invention and fully described construction embodying the several features thereof, what I claim is In device of the above description, the combination of a lamp-housing containing a double set of lenses, an incandescent lamp mounted in said lamp-housing for each of said lenses, said lamps connected to an electric circuit containing a source of E. 'M. F., a means provided for the simultaneous closure of said electric circuit through one of said lamps and the opening of said circuit through the other lamp, and reactance inserted in said lamp circuits.

In testimony whereof, that I claim the foregoing as my own, I have hereunto afiixed my hand to this specification in the presence of two subscribing witnesses, this 4th day of February, 1919.

WALTER G. PREDDEY.

Witnesses:

SAM DAVIS, M. O. DAVIS. 

